Improvement in cut-off valves for steam-engines



UNITED STATES PATENT OEEICE.

JAMES D. WHELPLEY, OF BOSTON, MASSACHUSETTS.

Specification forming part of Letters Patent No. 41,800, dated March 1, 1864.

.To a/ZZ whom it may concern:

Be it known that I, J AMEs D. WHELPLEY, of Boston, in the county of Suffolk and State of Massachusetts, have invented a new and useful Automatic Cut Off for Steam-Engines; and I do hereby declare that the following is a full, clear, and exact description of the construction and operation of the same, reference being had to the accompanying drawing, forming a part of this specication.

The drawing represents a vertical, central section through the cut-oft, and some of the parts `of a single-acting engine to which it is applied.

The lateral pressure of the steam in the induction-pipe, as it lowstoward the cylinder, varies (Within certain limits) inversely, as the velocity of the piston 2, and its momentum (within similar limits) varies directly as the velocity of the piston 2. The nature of my invention therefore consistsV in making use of both, or either, of these variations (which are complementary to each other) to regulate the velocity otl the engine, by causing them to move connections which will cut oft' the supply of steam to the cylinders at the desired moment. For this purpose I place a slightlymovable obstacle either directly in the path of the steam within the induction-pipe or in a closed side opening or cul-deseo from the same, to be moved or aiected by these variations. This obstacle may be a plate of metalc or other suitable substance, so poised in the path of the steam as to receive from it a slight reciprocating motion, or a complete or partial revolution, which shall cause a rod to press upon the valve-connections externally. The obstacle used may be a piston fitted steamtight into the opening in the side of the induction-pipe, or it may be the seat of the ordinary throttle-valve made movable in its chamber for the purpose described above, or it may be the supply-valves themselves, or metallic disks connected with them by rods or necks, and opposing resistance to the passage of the steam. In order to regulate the action of these contrivances, I provide a cover, with a hand-wheel to be operated outside the steam-cavities, by which I can allow more or less steam to reach and act upon them.

To illustrate the movements claimed, I have adopted an ordinary throttle-valve of which the seat is rendered slightly movable in its e., the expansive pressure and the momentum-are employed (as variables.)

To enable others skilled in the art to make and use my invention, I will now proceed to describe its construction and operation.

A is the induction or supply pipe leading from the boiler, and B is the cylindrical expanded chamber in which the movable obstruction is placed.

C is the continuation of the induction-pipe.

D is the chamber of the poppet-valve.

E is the steam-port leading into one end of the cylinder F.

G is a movable obstruction or valve-seat, which plays steam-iight in the cylindrical chamber B.

H is a yoke, the ends of which are conned to the top of the valve-seat G by means of screws c c.

I is the tubular support of the valve-seat G, attached to the center ot' the yoke H, and passing up through the top of the steamspringchamber N.

J is a piston, fast to the tubular support I Y and moving steam-tight in the cylinder N. The object of the piston J is to cause the valveseat G to resist the downward pressure of the steam in proportion to the pressure of the steam in the boiler.

The space in chamber N, above the piston J, operates as an air-spring, having' an outletpipe, o, for the gradual escape and entrance of air.

a is a spiral spring, by means of which the weight ofthe valve-seat G and of its appendages is exactly or nearly counterbalanced.

K is a throttle-valve, which may be lowered so as to completely close the opening in the valve-seat G, the space between said seat and valve affording a passage for the steam.

L is the supportin g-rod of the throttle-valve K, the upper end of said rod being provided with an external screw, b, which plays in an internal screw in the upper end ofthe tubular support I.

Mis a wheel attached to the top of the rod L, by means of which the valve K can be raised or depressed, so as to afford greater orj valve-seat G by means of screws d d.

P is a at or square rod. the upper end of which is fast to the yoke Q, said rod passing down through the stuffing-box R, as shown in the drawing, for the purpose hereinafter described. Y

S is a poppetvalve for closing the opening into the steamport E.

T is the rod to which the valve S is attached, passing through the stuiiing-box U and stay 1". The small end t of said rod passing through the'stufiingboxj is provided with a piston, 7c, which plays in the cylindrical springchamber g.

7L is a spring, by means ot which the valve S is closed. Y

j is a stuftingbox through which the rod t passes, the space between said stuffingfbox and the valve lc constituting an air-sprn g to ease the backward or closing motion ofthe valve S.

fis an outlet of the air-spring.

V is a depressible arm or continuation ot the rod T, being united to the latter by means i ot the pin m, and supported in a horizontal position by means ot' the spring Z.

W is a rod sliding' in the stays t" i', and form ing a continuation of the rod T. To the outer end of V is attached the foot X, which is worked by a cam, or its equivalent, in the usual manner for opening the valve S.'

In a double-acting engine ot' course tlure should be another post, ,E,and poppet-valve S, with its appendages, also, another pipe` similar to C, leading from the chamber B, and in this case, also, the rod P should have an oii'set just below the stuffing-box It, carrying another perpendicular rod like fw, the lower end of which would operate in a similar manner upon a second valve-rod during the second half-stroke of t the piston.

The space between the valve K and its seat G being regulated so as to admit the requisite amount ot' stean, it is obvious that in case the steam in motion acts in excess upon the upper surface of K, and G the latter will be depressed, forcing the end w of the rod P onto the Vdepressible arm V, the free eX- tremity of which will drop under the end of W, when the valve S will be instantly closed by the action of spring h. The point of action or excess is regulated by a larger or smaller opening of the valve. As this measures the quantity oi' steam passing through in a given i time, it fixes the maximum velocity of the piston.

Having thus described the construction and operation of my invention, what I claim as new, and desire to secure by Letters Patent, 1s

1. The employment of a slightlymovable piston, G, or its equivalent, substantially as set forth, and for the purpose described.

2. Connecting with the valve seat G a rod, P, the end of which shall move the depressible section V ofthe valve-rod, substantially as described.

3. The combination of the cover or valve K with the movable obstruction or valve-seat G, for the purpose of regulating the action of the latter in the chamber B, substantially as described.

4:. In combination with the movable obstruction G, the piston J for the purpose of balancing or counteracting the variations ot' steampressure in the boiler and pipe, substantially as described. 

